Dc voltage magneitude modifying arrangement



United States Patent 3,381,202 DC VOLTAGE MAGNITUDE MODIFYINGARRANGEMENT Russell D. Loucks, New Rochelle, N.Y., and Peter J.

Lupoli, Hamden, Conn., assignors to Technipower Incorporated, SouthNor-walk, Conn., a corporation of Connecticut Continuation-impart ofapplication Ser. No. 435,851,

Mar. 1, 1965.'This application Feb. 2, 1967, Ser- 10 Claims. (Cl. 321-2)ABSTRACT OF THE DKSCLOSURE A magnitude modifying DC voltage power supplyutilizing a switching transistor to control the output voltage, thattransistor being so connected as to have applied thereacross a voltageless than the output voltage.

This application is a continuation-in-part of our copending applicationSer. No. 435,851, filed March 1, 1965, entitled DC Voltage Step-upArrangement, and being assigned to the same assignee.

The present invention relates to a circuit arrangement for producing amagnitude-modified DC voltage with a high degree of efficiency andreliability.

There are many applications where a DC voltage supply is available butwhere it is desirable that a voltage be used which is higher than thatwhich the DC source is capable of providing. It has been proposed toproduce this stepped-up or increased output voltage by causing a currentto intermittently build up and decay through an inductance and utilizingthe increased voltage attendant upon such action to charge an outputcapacitor. The voltage-producing intermittent current through theinductance is controlled by switching means connected across the linebetween the inductance and the output capacitor, and the timing of thisswitching means, and in particular the time relationship between its onand off conditions, is varied in accordance with the voltage to whichthe output capacitor is charged, thereby to maintain that voltage at aproper value. The desirability of using an electronic switching means(one with no physically movable parts) is obvious, and transistors arepreferred in this connection, in part because of their high efliciency.

However, transistors are quite sensitive to the voltage to which theyare subjected. Hence the fact that the transistors employed forswitching purposes were subjected to the total stepped-up output voltagewas a definite drawback, particularly from the point of View ofreliability.

The switching transistor must be turned on and off very rapidly, and theprecise relationship between on-time and oif-time must be very preciselycontrolled if the steppedup output voltage is to be maintained at aconstant value. Electronic, and particularly solid state electronic,devices are desirable for controlling the switching transistor, but thearrangements which have been proposed in the past for controlling theswitching transistor have been quite complex and expensive, involving,for example, the use of silicon controlled rectifiers and a separatesaturablecore winding electromagnetically associated with thevoltage-increasing inductance to provide the signals necessary to causethe silicon controlled rectifier to function properly. The use of such aseparate winding required that each unit be tailor-made for a particularapplication, and because those windings operated on a saturationprinciple the units were sensitive to variations or ripple in the inputvoltage.

The prime object of the present invention is to overcome thesedisadvantages of the prior art circuitry. In

ice

particular, the circuitry of the present invention utilizes a transistorfor switching purposes but subjects that transistor to only a fractionof the total output voltage, thus greatly increasing the reliability andlife of its operation. In addition, an all-transistor control circuit isprovided for the switching transistor, thus eliminating the need forsilicon controlled rectifiers, and in an illustrated embodiment alsoeliminating the additional windings required in connection with the useof such rectifiers. As a result a circuit is produced which is capableof providing increased output voltages, when compared with the priorart, with a high degree of efiiciency, with an increased degree ofreliability, and at a lower cost. Moreover, the resultant apparatus ismore adaptable to different circuit applications, so that a singlestandard unit of wide utility can be engineered and produced. Such unitscan be smaller and lighter than prior art apparatus for the samepurpose.

These results are accomplished by utilizing, for the voltage-increasinginductance, a pair of inductively related winding sections, with theswitching transistor being connected to the line, which contains atleast one of the inductance sections, at a point between those twosections. Thus the switching transistor is subjected only to the maximumvoltage produced by one of those winding sections, whereas the outputvoltage is at a higher value, produced in one illustrated embodiment bythe two winding sections acting in aiding relationship and in the otherillustrated embodiment by the second section alone. The switchingtransistor is actuated between its on and off conditions by means of atransistorized flip-flop circuit which shifts back and forth from oneoperational status to the other, the existence of each status of theflip-flop circuit respectively actuating the switching transistor toeither its on-condition or its off-condition. The percentage of timethat the flip-flop circuit is in one status or another, and hence thepercentage of time that the switching transistor is on or 011?, iscontrolled in accordance with the output voltage by means of atransist-orized voltage sensing circuit which is in turn operativelyconnected to the flip-flop circuit. The system of the present inventionmay be inherently self-starting, and no special circuit elements need'be provided for that purpose.

Where the output winding section is not connected directly in serieswith the input winding section, as is the case in the second and thirdembodiments here specifically illustrated, either a step-up or astep-down characteristic can be obtained, and the voltage output can bemade to fall to zero when the switching transistor remains open ornon-conductive, thus preventing overloading in the case of a short inthe load circuit. In that type of arrangement it is preferred to sensethe output voltage and control the switching transistor in accordancetherewith. When this is done, additional windings may be provided fromwhich additional voltage outputs can be derived, and the regulationeffected by directly sensing one output voltage will accurately provideregulation for values for all of the other outputs.

To the accomplishment of the above, and to such other objects as mayhereinafter appear, the present invention relates to the circuitarrangement for a voltage step-up device as defined in the appendedclaims and as described in this specification, taken together with theaccompanying drawings, in which:

FIG. 1 is a simplified circuit diagram of a preferred embodiment of thesystem of the present invention, shown partially in block form;

FIG. 2 is a complete circuit diagram of one preferred embodiment of thepresent invention;

FIG. 3 is a simplified circuit diagram of another preferred embodimentof the present invention, shown partially in block form; and

FIG. 4 is a similar circuit diagram of yet another preferred embodiment.

In the embodiment of FIGS. 1 and 2, the voltage stepup arrangementcomprises a pair of lines 2 and 4 connecting input points 6 and 8 withoutput points 10 and 12 respectively. Any suitable DC voltage scource isadapted to be connected across the input points 6 and 8. That sourcemay, for example, be a fuel cell which produces a voltage ofapproximately one volt or it may be an AC source feeding through arectifier. In one of the lines, here shown as the line 2, an inductancegenerally designated 14 is connected. In accordance with the presentinvention, and as embodied in this particular embodiment, the inductance14 comprises a pair of serially connected and inductively associatedWinding sections 16 and 18, the reference numeral 20 representing apoint on the line 2 between the winding sections 16 and 18. Theinductance 14 may take the form of a dual-wound or center-tapped chokecoil. In series with the inductance 14, and on the output side thereof,is a rectifier 22 poled to permit ready current flow from input tooutput. A capacitor 24 is connected between the lines 2 and 4 on theoutput side of the rectifier 22.

A switching circuit 26 is connected between the points 20 and 28 on thelines 2 and 4 respectively. A flip-flop control circuit 30 isoperatively connected to the switching circuit 26, as indicated by theline 32. The flip-flop circuit 30, as the name implies, willperiodically shift from one status to another, and it will control theswitching circuit 26 accordingly. When the flip-flop circuit 30 is inone status it will cause the switching circuit 26 to be in its oncondition constituting a closed circuit between the points 20 and 28.When the flip-flop circuit 30 is in its other status it will cause theswitching circuit 26 to assume its off condition, constituting an opencircuit between the points 20 and 28. The timing of the shifting of theflip-flop circuit 30 from one status to the other is controlled, asindicated by the line 34, by a sensing circuit 36 which is connected toan adjustable point 38 on the resistor 40, which, in series with theresistor 42, is connected across the lines 2 and 4 between points 44 and46. The resistors 40 and 42, it will be noted, are connected at theoutput side of the rectifier 22, so that voltage at the point 38 willrepresent a predetermined proportion of the output voltage across theoutput points 10 and 12. Adjustment of the position of the point 38along the resistor 40 will permit control of that output voltage.

The circuit, broadly considered, functions as follows: When theswitching circuit 26 goes from off to on a current will flowtherethrough from the input voltage source connected across the inputpoints 6 and 8 and through the winding section 16 of the inductance 14.Because of the inductance thereof that current will slowly build up.When the switching circuit 26 then goes from on to off, the storedenergy in the winding section 16 will tend to maintain the currentflowing therethrough, which current will slowly decay. As this occursthe magnetic field associated with the Winding section 16 will collapse,thus inducing a voltage in the Winding section 16 which adds to thevoltage derived from the input source connected across the points 6 and8. This increase in voltage, and the current accompanying it, cannotpass through the switching circuit 26 because the switch is open, so itpasses through the rectifier 22 and charges the output capacitor 24. Therectifier 22 prevents reverse flow from the output capacitor 24. For solong as the switching circuit 26 continues its shift between on and otfconditions, impulses of additional current will be supplied to theoutput capacitor 24, and by controlling the time of switching of theswitching circuit 26, and more particularly the relation between thetime that the switch is closed and the time that the switch is open, theoutput capacitor 24 can be kept charged to a desired value, thatconstituting the output voltage across the output points 10 and 12.

As thus far described only the action of the winding section 16 has beenconsidered. Because of the relationship between the Winding sections 16and 18, the flow of current through the winding section 18 when theswitching circuit 26 is open or off will cause an additional voltage tobe generated in that winding section 18 which, if the winding section 18is wound in an appropriate direction, will add to the voltage incrementgenerated by the winding section 16. However, since the switchingcircuit 26 is connected to the point 20 located in advance of thewinding section 18, the switching circuit 26 itself will not besubjected to the voltage increment produced by the winding section 18,but will only be subjected to the voltage increment produced by thewinding section 16. Hence the circuit elements comprising the switchingcircuit 26 will be subjected to a voltage greater than the input voltageapplied across the input points 6 and 8 but less than the total outputvoltage applied across the output points 10 and 12. As has been pointedout, this gives rise to a marked increase in reliability of operation.

Turning now to FIG. 2, which represents a circuit diagram of a preferredembodiment of the present invention, the sensing circuit 36, flip-flopcontrol circuit 30 and switching circuit 26 are enclosed within brokenline boxes to which the appropriate reference numerals have beenapplied. The sensing circuit 36 comprises a transistor 38 the base ofwhich is connected, by lead 50, to the point 38 on resistor 40. Aresistor 52 and a Zener diode 54 are connected in series between points56 and 58 on the lines 2 and 4 respectively, and the emitter oftransistor 48 is connected, via resistor 60, to point 62 located betweenthe resistor 52 and the Zener diode 54. The collector of the transistor48 is connected by lead 64 and resistor 66 to the base of transistor 68forming a part of the control circuit 30. The collector of transistor 68is connected by resistors 70 and 72 to lead 74, which is in turnconnected, at point 76, to the input point 6 and line 2. The flip-flopportion of the control circuit 30 is defined by transistors 78 and 80.The base of transistor 78 is connected by lead 82 to point 84 betweenthe resistors 70 and 72. A resistor 86 is connected in the line 2, andthe emitters of transistors 78 and are connected, via leads 88 and 90respectively and resistor 92, to point 94 at the output end of theresistor 86. The collector of transistor 80 is connected via resistors96 and 98 to line 4. The collector of transistor 78 is connected by lead100 and resistor 102 to point 104, and the base of transistor 80 isconnected by lead 105 and lead 100 to the emitter of transistor 78. Aresistor 106 is connected between line 74 and point 108 on lead 64, anda rectifier 110 is connected between points 104 and 108 and poled towardpoint 108. A Zener diode 112 is connected between point 104 and lead 74.

The switching circuit 26 comprises transistors 114, 116, 118 and 120.Transistors 114, 116 and 118 have their emitter-collector circuitsconnected in parallel between line 4 and line 2, vialead 122. Resistors124 and 126 are connected between line 4 and the emitters of transistors116 and 118 respectively. The base of transistor 114 is connected bylead 127 to the emitter of transistor 116, and the base of transistor116 is connected by lead 128 to the emitter of transistor 118. The baseof transistor 118 is connected by lead 130 to point 132. The point 132is connected by resistor 134 to point 104, and is connected by lead 136to the collector of transistor 120, the emitter of that transistor beingconnected by lead 138 to the line 4. The base of transistor 120 isconnected by lead 140 to point 142 located between the resistors 96 and98.

The operation of the circuit is as follows: a bias is applied to thebase of transistor 48 in accordance with the output voltage acrossoutput points 10 and 12. A bias is applied to the emitter of transistor48 as determined by the voltage reference Zener diode 54. Hence thetransistor 48 compares a predetermined fraction of the output voltagewith the reference voltage and its emitter-collector current iscontrolled in accordance therewith, that current flowing through theresistor 106. The amount of current flowing through the resistor 106determines the bias on the base of transistor 68, thereby controllingthe amount of emitter-collector current for that transistor, saidemitter-collector current flowing through the resistors 70 and 72. Theamount of current flowing through the resistor 72 controls the bias onthe base of transistor 78.

The transistors 78 and 80 constitute a flip-flop circuit whose action iscontrolled by the bias on the base of transistor 78 and by the voltagedrop across the resistor 86 due to current flow into the inductance 14.In one status of the flip-flop circuit emitter-collector current willflow only through the transistor 78; in the other status of thatflip-flop circuit emitter-collector current will flow only through thetransistor 80. When emitter-collector current flows only through thetransistor 80 the transistor 120 will be saturated and will thus by-passto line 4 the base current for transistor 118. Hence transistor 118 willbe rendered non-conductive, and transistors 114 and 116 will be renderednon-conductive, the switching circuit 26 thus being placed in off oropen circuit condition. When emitter-collector current flows throughtransistor 78, transistor 120 Will be non-conductive, base current willbe provided to transistor 118, and it and transistors 114 and 116 willbe rendered conductive with regard to their emitter-collector circuits,thus placing the switching circuit 26 in its on or closed circuitcondition. The flip-flop transistors 78 and 80 are so connected thatfirst one and then the other will be rendered conductive as determinedby the voltage output across the points and 12 and the voltage dropproduced in resistor 86 by the current flowing through the inductance14. With the transistor 78 conductive, and hence with the switchingtransistors 114-118 on, a current will flow through the resistor 86 andthe inductance winding section 16. The magnitude of that current willbuild up in accordance with the inductance characteristic of the windingsection 16. The conductivity status of transistor 78 will be controlledby the bias applied to its base (that in turn controlled by the outputvoltage through the transistor 48) and the voltage drop produced inresistor 86 by the flow of said current. When that current reaches apredetermined magnitude the bias on the emitter of transistor 78 will bechanged sufiiciently to turn that transistor olf and to turn thetransistor 80 on by changing the bias on its base (the circuit willfiop), this being effective to turn the switching transistors 114-118off. The cessation of the collector-emitter current of the transistor 78will return the base of transistor 80 to the original bias which existedbefore the transistor 78 became conductive. As the current through theresistor 86 and the winding section 16 diminishes, the bias on theemitters of the transistors 78 and 80 will change, and the point in timeat which the transistor 78 will again become conductive (the circuitwill flip) will be determined by the bias on the base of transistor 78which is, as we have seen, controlled by the output voltage.

It will be appreciated from the above that the circuitry of the presentinvention includes all of the advantages of utilizing transistors toeffectuate the necessary switching, without having to subject thoseswitching transistors 114-118 to the full output voltage, and furtherthat the control of the switching action is efltected by anall-transistor circuit which requires no special windings or cores forcontrol purposes, and which is therefore appreciably less expensive thanprior art constructions.

A very significant advantage of the circuitry of the present invention,apart from those already set forth, is the flexibility of use of thecircuitry involved. Where separate windings are required, as whensilicon controlled rectifiers are employed, a given winding can be usedonly with a very limited number of applications. If the circuitrequirements vary to any appreciable degree, separate windings must bedesigned and used. This limitation is not applicable to the instantcircuitry, a standard embodiment of which can be used without change inconnection with a very wide variety of difi'erent circuit applications.Moreover, silicon controlled rectifier control involves winding coresaturation. This requires the use of a filtered DC input, since ripplein that input might affect the saturation of the core and hence theswitching control of the silicon controlled rectifier. With thecircuitry of the present invention, by way of contrast, an unfilteredinput can be used, since ripple has no appreciable etfect on theoperation of the instant circuit.

Purely by way of exemplification, circuit components having thefollowing values may be used:

Inductance 14-4 millihenries, center-tapped Capacitor 246000 mfd.Resistor 40-1K ohms Resistor 421K ohms Transistor 482N305 3 Resistor52-3300 ohms for 28 volts DC input Zener Diode 54-1N751 Resistor 60-1Kohms Resistor 661K ohms Transistor 68-2N3053 Resistor 70--1K ohmsResistor 72-470 ohms Transistor 78-2N3250 Transistor 80 --2N3250Resistor 86.05 ohm Resistor 92-100 ohms Resistor 964.7K ohms Resistor98-1K ohms Resistor 182-1K ohms Resistor 1062.2K ohms Zener Diode1121N751 Transistor 1142N3442 Transistor 1162N 3441 Transistor118--2N305 3 Transistor 1202N3053 Resistor 12410 ohms Resistor 1264.7ohms Resistor 134--1K ohms In the embodiment of FIGS. 1 and 2 thewinding sections 16 and 18 Were conductively connected in series in theline 2 between input point 6 and output point 10. In the embodiment ofFIG. 3 this is not the case. The inductance section 16a is connectedbetween lines 2 and 4 in series with the switching circuit 26. Theinductance section 18a, inductively associated with the section 16a, hasone end connected by lead 141 to line 4, the other end thereof beingconnected via rectifier 22 to output point 10. Condenser 24 is connectedbetween the line 4 and the output end of the rectifier 22. A sensingcircuit 36 is connected across output points 10 and 12 so as to sensethe output voltage and, through an amplifier circuit 143 and a controlcircuit 30a, controls the time sequence of the switching circuit 26 in amanner comparable to that involved in the embodiment of FIGS. 1 and 2.The arrange ment of FIG. 3 functions in substantially the same fashionas that of FIGS. 1 and 2 except that the output voltage is developedexclusively from the inductance section 18a, the appropriate voltagesbeing induced in that section by the flow and interruption of current inthe inductance section 16a as produced by switching circuit 26. Thearrangement of FIG. 3 has the advantage that it can be used either forvoltage step-up or step-down, depending upon the turns ratio between theinductance sections 16a and 16b respectively. Moreover, because theoutput inductance section 18a is isolated from the input inductancesection 16a, the output voltage across the output points 10 and 12 fallsto Zero when the switching circuit 26 is retained in open-circuitcondition (in the embodiment of FIGS. 1 and 2 the output voltage would,under those circumstances, equal the input voltage). Hence in theembodiment of FIG. 3 it there should be a short circuit in the circuitto which the output points 10 and 12 are connected,

the rise in output current can be sensed (by well-known means), and usedto cause the switching circuit 26 to turn off, and hence the outputvoltage would fall to zero, preventing an overload condition.

The embodiment of FIG. 4 is similar to that of FIG. 3, and correspondingreference numerals are applied to corresponding parts. In addition, theinductance 14 is provided with a third winding section 18a, whichisconnected by lines 144 and 146 to output points 10 and 12 respectively,a rectifier 22 being connected in line 144 and a capacitor 24 beingconnected across the output points 10' and 12. In this way a givensystem can have two different output voltages, across the points It), 12and 10', 12 respectively, the magnitude of those voltage outputs beingdetermined by the number of turns in the inductance winding sections1811 and 18a respectively. Since the control of the switching circuit 26is effected by sensing one of the output voltages (that across theoutput points 10 and 12), the resulting voltage regulation will beefiective on the other output voltage across the points 10' and 12. Itwill be understood that more than one extra inductance section 18a,together with its associated rectifier 22' and condenser 24', could beemployed to produce as many difierent and isolated output voltages asdesired, with all of those output voltages being effectively regulatedto take into account variations in input voltage.

While but a limited number of embodiments of the present invention havebeen here disclosed, it will be apparent that many variations may bemade therein, all within the scope of the invention, as defined in thefollowing claims.

We claim:

1. A DC voltage magnitude modifying arrangement comprising a DC input, aDC output, and a circuit operatively connecting said input and output,said circuit comprising inductance means and a rectifier operativelyconnected-between said input and output, said inductance meanscomprising first and second inductively related sections, at least saidsecond section being conductively connected to said output via saidrectifier, at least said first section being conductively connected tosaid input, a capacitor connected across said output on the output sideof said rectifier, switch means comprising electronic valve meansactuatable to on and otf conditions re spectively, said switch meansbeing conductively connected to said first section of said inductancemeans in a manner independent of said second section of said inductancemeans, and switch actuating means for sensing the voltage at said outputand actuating said switch means between said on and oif conditions in amanner related to said sensed output voltage, in which said first andsecond sections of said inductance means are conductively connected inseries between said input and said output, and in which said switchactuating means comprises a dip flop circuit, an output voltage sensingcircuit, means operatively connecting said fiip-fiop'circuit to saidoutput voltage sensing circuit so that the timing of the flip-flopaction of said flip-flop circuit is controlled by said sensing circuit,and an operative connection between said flipflop circuit and saidswitch means, whereby the condition of said switch means is controlledby the status of said flip-flop circuit.

2. A DC voltage magnitude modifying arrangement comprising a DC input, aDC output, and a circuit operatively connecting said input and output,said circuit comprising inductance means and a rectifier operativelyconnected between said input and output, said inductance meanscomprising first and second inductively related sections, at least saidsecond section being conductively connected to said output via saidrectifier, at least said first section being conductively connected tosaid input, a capacitor connected across said output on the output sideof said rectifier, switch means comprising electronic valve meansactuatable to on and off conditions respectively, said switch meansbeing conductively connected to said first section of said inductancemeans in a manner independent of said second section of said inductancemeans, and switch actuating means for sensing the voltage at said outputand actuating said switch means between said on and off conditions in amanner related to said sensed output voltage, in which said first andsecond sections of said inductance means are conductively connected inseries between said input and said output, and in which said switchactuating means comprises a flip-flop circuit, an output voltage sensingcircuit, means operatively connecting said flip-flop circuit to saidoutput voltage sensing circuit so that the timing of the flip-flopaction of said flip-flop circuit is controlled by said sensing circuit,and an operative connection between said flipflop circuit and saidswitch means, whereby the condition of said switch means is controlledby the status of said flip-flop circuit, and in which said voltagesensing circuit comprises a transistor having an output circuit and aninput circuit, said input circuit being operatively connected to saidoutput voltage, said output circuit being operatively connected to saidflip-flop circuit.

3. A DC voltage magnitude modifying arrangement comprising a DC input, aDC output, and a circuit operatively connecting said input and output,said circuit comprising inductance means and a rectifier operativelyconnected between said input and output, said inductance meanscomprising first and second inductively related sections, at least saidsecond section being conductively connected to said output via saidrectifier, at least said first section being conductively connected tosaid input, a capacitor connected across said output on the output sideof said rectifier, switch means comprising electronic valve meansactuatable to on and off conditions respectively, said switch meansbeing conductively connected to said first section of said inductancemeans in a manner independent of said second section of said inductancemeans, and switch actuating means for sensing the voltage at said outputand actuating said switch means between said on and off conditions in amanner related to said sensed output voltage, in which said first andsecond sections of said inductance means are in non-conductive inductiverelation with one another and said input and output are operativelyconnected substantially only by said inductive relation between saidinductance means sections and in which said switch actuating meanscomprises a flip-flop circuit, an output voltage sensing circuit, meansoperatively connecting said flip-flop circuit to said output voltagesensing circuit so that the timing of the flip-flop action of saidflip-flop circuit is controlled by said sensing circuit, and anoperative connection between said flip-flop circuit and said switchmeans, whereby the condition of said switch means is controlled by thestatus of said flip-flop circuit.

4. A DC voltage magnitude modifying arrangement comprising a DC input, aDC output, and a circuit operatively connecting said input and output,said circuit comprising inductance means and a rectifier operativelyconnected between said input and output, said inductance meanscomprising first and second inductively related sections, at least saidsecond section being conductively connected to said output via saidrectifier, at least said first section being conductively connected tosaid input, a capacitor connected across said output on the output sideof said rectifier, switch means comprising electronic valve meansactuatable to on and ofi conditions respectively, said switch meansbeing conductively connected to said first section of said inductancemeans in a manner independent of said second section of said inductancemeans, and switch actuating means for sensing the voltage at said outputand actuating said switch means between said on and off conditions in amanner related to said sensed output voltage, in which said firs-t andsecond sections of said inductance means'are in non-conductive inductiverelatlon with one another and said input and output are operativelyconnected substantially only by said inductive relation between saidinductance means sections, and in which said switch actuating meanscomprises a flip-flop circuit, an output voltage sensing circuit, meansoperatively conecting said flip-flop circuit to said output voltagesensing circuit so that the timing of the flip-flop action of saidflip-flop circuit is controlled by said sensing circuit, and anoperative connection between said flip-flop circuit and said switchmeans, whereby the condition of said switch means is controlled by thestatus of said flip-flop circuit, and in which said voltage sensingcircuit comprises a transistor having an output circuit and an inputcircuit, said input circuit being operatively connected to said outputvoltage, said output circuit being operatively connected to saidflip-flop circuit.

5. A DC voltage magnitude modifying arrangement comprising a DC input, aDC output, and a circuit operatively connecting said input and output,said circuit comprising inductance means and a rectifier operativelyconnected between said input and output, said inductance meanscomprising first and second inductively related sections, at least saidsecond section being conductively connected to said output via saidrectifier, at least said first section being conductively connected tosaid input, a capacitor connected across said output on the output sideof said rectifier, switch means comprising electronic value meansactuatable to on and off conditions respectively, said switch meansbeing conductively connected to said first section of said inductancemeans in a manner independent of said second section of said inductancemeans, and switch actuating means for sensing the voltage at said outputand actuating said switch means between said on and off conditions in amanner related to said sensed output voltage, in which said first andsecond sections of said inductance means are in non-conductive inductiverelation with one another and said input and output are operativelyconnected substantially only by said inductive relation between saidinductance means sections, and in which said inductance means comprisesa third section inductively and non-conductively related to said firstand second sections, an additional output, said third section of saidinductance means being conductively connected to said additional output,a capacitor connected across said additional output, and a rectifieroperatively connected between said third section of said inductancemeans and said additional output.

6. A DC voltage magnitude modifying arangement comprising a DC input, aDC output, and a pair of lines electrically connecting said input andsaid output, an inductance and a rectifier connected in series in one ofsaid lines, said inductance having an input end, a capacitor connectedacross said lines from a point on said one line between said rectifierand said output, switch means actuatable to on and off conditionsrespectively connected between the other of said lines and a point onsaid inductance spaced from the input end thereof, means for sensingsaid voltage output, a flip-flop circuit connected between said voltagesensing means and said switch means, means for controlling the timing ofthe action of said flipflop means in shifting from one status to theother in accordance with the sensed output voltage, and means forcontrolling the on-off condition of said switch means in accordance withthe status of said flip-flop means.

7. The DC voltage magnitude modifying arrangement of claim 6, in whichsaid voltage sensing circuit comprises a transistor having an outputcircuit and an input circuit, said input circuit being operativelyconnected to said output voltage, said output circuit being operativelyconnected to said flip-flop circuit.

8. The DC voltage magnitude modifying arrangement of claim 6, in whichsaid switch means and said flip-flop circuit are transistorized.

9. The DC voltage magnitude modifying arrangement of claim 8, in whichsaid means for sensing said voltage output comprises a transistor havingan output circuit and an input circuit, said input circuit beingoperatively connected to said DC output, said output circuit beingoperatively connected to said flip-flop circuit.

10. In the DC voltage magnitude modifying arrange ment of claim 6, saidswitch means comprising a transistor, a resistor in said one of saidlines between said inductance and the corresponding input point, saidflip-flop circuit comprising a pair of transistors connected inflip-flop manner across said lines from a point on said one line betweensaid inductance and said resistor, said switchcontrolling meanscomprising a transistor operatively connected between said flip-floptransistors and said switch means transistor for controlling the on-offcondition of the latter in accordance with the flip-flop status of theformer.

References Cited UNITED STATES PATENTS 3,331,008 7/1967 Bedford 321-23,113,275 12/1963 Minter 321-2 X 3,263,099 7/1966 Bedford 307-1093,300,705 8/1963 Hunstad 32l-2 FOREIGN PATENTS 1,053,591 5/1959 Germany.

OTHER REFERENCES Bedford/Hoft, Principles of Inverter Circuits, JohnWiley & Sons, Inc., 1964, p. 339.

JOHN F. COUCH, Primary Examiner.

WARREN E. RAY, Examiner.

W. H. BEHA, Assistant Examiner.

